TY - JOUR

T1 - RARE EARTH COMPOSITION OF FLUORITES AS AN INDICATOR OF THE ORIGIN OF CARBONATITES OF CENTRAL TUVA AND EASTERN TAIMYR

AU - Goryunova, Valentina O.

AU - Prokopyev, Ilya R.

AU - Doroshkevich, Anna G.

AU - Starikova, Anastasiya E.

AU - Proskurnin, Vasily F.

AU - Saltanov, Vasily A.

N1 - The geology of the objects was studied within the framework of state assignments from the Institute of Geology and Mineralogy SB RAS (122041400241-5) and the Geological Institute SB RAS (\u0410\u0410\u0410\u041021-121011390002-2). Studies of carbonatites of Tuva were carried out according to the state order of TuviKOPR SB RAS No. 121031500140-2 (FUFS-2021-0002). Research on the carbonatites of Western Transbaikalia was carried out within the framework of the Russian Science Foundation project 22-17-00078

PY - 2024

Y1 - 2024

N2 - The mineral fluorite (CaF2) has wide variations in physicochemical conditions of formation and crystallizes in magmatic, hydrothermal and sedimentary processes. Rare Earth Elements in minerals сan indicate parameters of its formation, therefore it can be considered as geochemical markers or indicator of the genetic characteristics of fluorite-bearing rocks, including ore metallogenic specificity. In this work, the behavior of rare earth elements (REE) in fluorites of carbonatites of folded formation belts is studied using the example of polymetallic calciocarbonatites of Eastern Taimyr – ore fields Orientirnoye and Zeleninskoye, and Fe-F-REE siderite carbonatites of Central Tuva (Central Asian folded region) – Karasug and Ulatai ore fields. The objects have a number of similar geological and genetic characteristics: the rocks are located in tectonic fault zones formed under conditions of rifting and intraplate tectonic-magmatic activity. Carbonatite ore bodies take the form of dykes, stockworks, stocks and explosion pipes, and the main rock-forming minerals are calcite and siderite, fluorite, barite and bastnäsite-(Ce). The quantitative rare earth composition (La-Lu, Sr, Y, U and Th) of fluorites was determined using the LA-ICP MS and SEM-EPMA methods. Studies of the rare earth composition of fluorites have shown that objects have their own characteristics of REE distribution, reflecting the specifics of crystallization of the mineral. Fluorites of the East Taimyr region are sharply different and have signs of a crustal component – low elemental contents (∑REE < 2.8 ppm), weak negative Ce and Yb anomalies. However, the predominance of medium REE over light and heavy REE, namely the dome-shaped configuration of the spectra, can be explained by atypical magmatic genesis associated with interaction with the crustal component. Fluorites of carbonatites of the Karasug and Ulatay fields are characterized by the highest concentrations of rare earth elements (∑REE = 502–7,352 ppm). Chondrite-normalized REE values showed that fluorites are divided into two types. The first type is characterized by a sharp predominance of light elements over heavy ones and a positive europium anomaly (Eu/Eu)n* up to 3.7). Depletion of light rare earth elements and a gentle slope of the spectra characterize the second type. Moreover, the only difference between the Karasug and Ulatai fluorites of the second type is the significant depletion of La in the first type. The results of the study showed that fluorites have certain distribution configurations of rare earths, which reflects the characteristics of the mineral crystallization environment for each object and characterizes the specific composition of fluorites of folded formation belts.

AB - The mineral fluorite (CaF2) has wide variations in physicochemical conditions of formation and crystallizes in magmatic, hydrothermal and sedimentary processes. Rare Earth Elements in minerals сan indicate parameters of its formation, therefore it can be considered as geochemical markers or indicator of the genetic characteristics of fluorite-bearing rocks, including ore metallogenic specificity. In this work, the behavior of rare earth elements (REE) in fluorites of carbonatites of folded formation belts is studied using the example of polymetallic calciocarbonatites of Eastern Taimyr – ore fields Orientirnoye and Zeleninskoye, and Fe-F-REE siderite carbonatites of Central Tuva (Central Asian folded region) – Karasug and Ulatai ore fields. The objects have a number of similar geological and genetic characteristics: the rocks are located in tectonic fault zones formed under conditions of rifting and intraplate tectonic-magmatic activity. Carbonatite ore bodies take the form of dykes, stockworks, stocks and explosion pipes, and the main rock-forming minerals are calcite and siderite, fluorite, barite and bastnäsite-(Ce). The quantitative rare earth composition (La-Lu, Sr, Y, U and Th) of fluorites was determined using the LA-ICP MS and SEM-EPMA methods. Studies of the rare earth composition of fluorites have shown that objects have their own characteristics of REE distribution, reflecting the specifics of crystallization of the mineral. Fluorites of the East Taimyr region are sharply different and have signs of a crustal component – low elemental contents (∑REE < 2.8 ppm), weak negative Ce and Yb anomalies. However, the predominance of medium REE over light and heavy REE, namely the dome-shaped configuration of the spectra, can be explained by atypical magmatic genesis associated with interaction with the crustal component. Fluorites of carbonatites of the Karasug and Ulatay fields are characterized by the highest concentrations of rare earth elements (∑REE = 502–7,352 ppm). Chondrite-normalized REE values showed that fluorites are divided into two types. The first type is characterized by a sharp predominance of light elements over heavy ones and a positive europium anomaly (Eu/Eu)n* up to 3.7). Depletion of light rare earth elements and a gentle slope of the spectra characterize the second type. Moreover, the only difference between the Karasug and Ulatai fluorites of the second type is the significant depletion of La in the first type. The results of the study showed that fluorites have certain distribution configurations of rare earths, which reflects the characteristics of the mineral crystallization environment for each object and characterizes the specific composition of fluorites of folded formation belts.

KW - Arctic

KW - Taimyr

KW - Tuva

KW - carbonatites

KW - fluorite

KW - rare earth

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85209189110&origin=inward&txGid=6f9e6e5bd6becaba0042d5102ddac948

UR - https://www.mendeley.com/catalogue/06789587-cc83-32e8-ac7c-060eeb934479/

U2 - 10.17223/25421379/32/2

DO - 10.17223/25421379/32/2

M3 - Article

VL - 2024

SP - 10

EP - 20

JO - Геосферные исследования

JF - Геосферные исследования

SN - 2542-1379

IS - 3

ER -